Erect annual 20–120 cm tall; stem slender, often with numerous ascending branches and shorter flowering branches above, usually densely silvery appressed pubescent, elsewhere sometimes sparsely puberulous to subglabrous. Leaves mostly 3-foliolate, uppermost sometimes 1-foliolate; leaflets 10–20(30) × 0.5–2.5(4) mm, linear-oblanceolate, appressed puberulous beneath; petiole 1–7(12) mm long; stipules 0. Terminal racemes 6–25 cm long, laxly 10–40-flowered, shorter on lateral branches, sometimes developing a few flowers in the axils below; bracts 1–4 mm long, shortly linear-elliptic to linear-subulate; pedicel 1.5–4 mm long, with setaceous bracteoles. Calyx 3–3.5 mm long, usually silvery tomentellous, elsewhere sometimes subglabrous; upper lobes rather broadly triangular, often slightly acuminate, ± twice as long as the tube. Standard obovate to oblate, pale yellow, marked red at the base inside, lined red outside, tomentellous outside or elsewhere sometimes puberulous only near the apex; wings longer than the keel; keel 4–5 mm long, subangular, with a tapered twisted beak. Pod sessile, 4–5 × 3.5–4 mm, ovoid-globose, puberulous, 2-seeded. Seeds 2.5–3 mm long, rounded-cordiform.
